Page 244 - parasitology for medical and clinical laboratoryprofessionals

224 CHAPTER 10

and cleaning should include furniture, mattresses, bed
MACROSCOPIC DIAGNOSTIC frames, walls, and baseboards in order to remove nesting

FEATURE (REQUIRES sites for these insects. Secondary infections may occur
from scratching the bedbug bites.
MAGNIFYING GLASS IN SOME
CASES)
Leeches

General Classification—Insect The term leech is applied to any of the annelids from the
class Hirudinea, especially Hirudo medicinalis. Some
Organism Cimex lectularis species are bloodsuckers and were once used to draw
Specimen Required Individual organism, blood out of those who were ill. These organisms are
usually obtained from parasitic in that they require sustenance from a victim in
skin or bed linens the form of blood, so medical practice in the past has in-
Stage Adult cluded the use of leeches for bleeding areas of the body.
Color & Appearance Reddish (newly Even today leeches are used to remove blood from large
hatched are bruises and are available from scientific supply houses.
translucent) The leech has not been known to transmit any diseases
Size Adult is 4–5 mm in to its human hosts.
length; 1.5–3 mm
in width
Shape Flat and oval Tooth Amoebae
Motility Nocturnal crawling
The amoeba Entameba gingivalis is a microscopic para-
site that hides in the tiny crevices where the teeth meet
the gums. Brushing does not remove them because of
requires several days to use as much as 1 mL of blood their ability to assume different shapes that enable them
from a victim, infants have been known to develop ane- to fit into minuscule hiding places. These organisms
mia from blood loss to these creatures (Figure 10-15). may be considered beneficial organisms because they
It is possible, but not proven, that the transmission of ingest mouth bacteria that may cause inflammation. But
hepatitis B and perhaps some of the other strains of with poor mouth hygiene, their numbers may proliferate
hepatitis have occurred through bedbug bites. Insecti- and they may become harmful when the lack of hygiene
cides are required for ridding an area of these parasites forces them to multiply too quickly.

SUMMARY

Ectoparasites derive their nourishment from the outside of may infest large groups of people and even large cities.
the body, primarily the skin, but also for some species, tak- Lice are capable of infesting a variety of hosts, as they are
ing advantage of either the host’s blood supply or debris adapted with structures that allow them to cling tightly
on the skin of the host. Other ectoparasites exist by eating to hair, fur, and feathers. The range of potential hosts for
the bacteria on the skin of the host. There are several major lice includes some aquatic creatures as well as land mam-
types of ectoparasites that plague human beings. Lice and mals, birds, and others.
mites are the two major groups that include four common Close contact with an infected person is required
genera, three of which are lice and one of which is classified to transfer the organism because lice cannot jump or fly.
as a mite. Fleas and ticks are also considered ectoparasites. Lice chiefly occupy crowded areas such as refugee camps
Infestations of lice include Pediculus humanus and and prisons due to the poor sanitation and hygiene that
Pthirus pubis as the best-known representatives, and foster the growth of these infestations. Some lice may be